Spherical plain bearing assemblies typically comprise a ball positioned for rotational movement in an outer ring. The ball defines an outer surface, and the outer ring defines an inner surface contoured to receive and retain the ball therein such that the outer surface of the ball is in sliding engagement with the inner surface of the outer ring. Contamination of the sliding engagement surfaces, namely, the outer surface of the ball and the inner surface of the outer ring, is one of the leading causes of bearing damage. Typically, the spherical plain bearing assembly includes a single sealing arrangement on opposing sides thereof, wherein a seal is provided in a single groove for retaining lubrication between the sliding engagement surfaces and for inhibiting the ingress of dirt, water, particulate matter, and other contaminants to the sliding engagement surfaces.
For example, a single SpreadLock® type seal is positioned in each single groove positioned on opposing sides of a spherical bearing, as described in U.S. Pat. No. 6,626,575, the subject matter of which is incorporated herein by reference. Typically, a single groove on each of opposing sides of the spherical bearing was employed to minimize the axial dimensions of the bearing while maximizing the load bearing capability of and sliding engagement between, the outer surface of the ball and the inner surface of the outer ring. Thus, use of more than one groove or seal per bearing side was not considered.
However, some seals do not keep all contaminants out of the bearing and can impair motion of the inner member relative to the outer member. In addition, movement of the inner member relative to the outer member can cause the seal to become dislodged. A means of preventing contaminant entry that would not impair relative motion of the inner member and the outer member, would better keep contaminants out of the bearing and would not allow the seal to be dislodged has long been sought in the industry.